This laboratory uses mutants in the bacterium Excherichia coli and in the yeast Saccharomyces cerevisiae to study the genetics and function of glycolysis, an important pathway in most cells. The present application is principally for studies of phosphofructokinase. In E. coli there are, in various mutants, enzymes of three different types and different effector responses. To a degree, these enzymes act adequately in glycolysis, but there are differences in growth, particularly in gluconeogenesis. The proposed work is for rationalizing the differences by comparative study of the three enzymes, of metabolism, including futile cycling, and of metabolite concentrations in the several strains. In the yeast, the main project is to explain why phosphofructokinase mutants grow well on glucose, and includes enzymological studies and metabolic analysis of several mutants.